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The traditional approach to formulating building codes often is slow and labor-intensive, and may struggle to keep pace with the rapid evolution of technology and domain findings. Overcoming such challenges necessitates a methodology that streamlines the modernization of codal provisions. This paper proposes a machine learning (ML) approach to append a variety of codal provisions, including those of empirical, statistical, and theoretical natures. In this approach, a codal provision (i.e., equation) is analyzed to trace its properties (e.g., engineering intuition and causal logic). Then a ML model is tailored to preserve the same properties and satisfy a collection of similarity and performance measures until declared equivalent to the provision at hand. The resulting ML model harnesses the predictive capabilities of ML while arriving at predictions similar to the codal provision used to train the ML model, and hence it becomes possible to use in lieu of the codal expression. This approach was examined successfully for seven structural engineering phenomena contained within various building codes, including those in North America and Australia. The findings suggest that the proposed approach could lay the groundwork for implementing ML in the development of future building codes. [ABSTRACT FROM AUTHOR]

Accurate numerical modeling of structural components is necessary for both performance-based designs of new structures and performance assessments of existing structures. Steel special concentrically braced frames (SCBFs) represent a large portfolio of steel buildings in areas of high seismicity, especially in North America. Therefore, it is necessary to critically study the accuracy of available numerical models for SCBFs and propose improvements to them, if necessary. This requires forming a database of high-fidelity benchmark experimental results for SCBFs against which models can be compared. This paper presents multielement hybrid simulations on a steel SCBF, as a representation of systems with highly unsymmetrical hysteretic response. A representative buckling brace specimen is developed and verified through reversed-cyclic tests to physically capture the response of SCBFs in the experiments. 2-element and 4-element pseudo-dynamic hybrid simulations are carried out on the reference SCBF using the University of Toronto Ten-Element Hybrid Simulation Platform (UT10). The experimental results from the multielement tests are compared with numerical simulations in detail using the available numerical models, which are observed to predict the response well. [ABSTRACT FROM AUTHOR]

This paper examines the accuracy of equations specified by the North American and Australasian steel structures codes for determining the net section tension capacity of a channel brace. It points out that there are three distinct factors affecting the net section efficiency of a cold-formed steel channel brace bolted at the web. These factors include (1) the in-plane shear lag associated with stress concentration around a bolt hole that is also present in flat sheets, (2) the out-of-plane shear lag that is also present in an I-section bolted at the flanges only, and (3) the bending moment arising from the connection eccentricity with respect to the neutral axis. Each of the relevant factors is explicitly incorporated into the equation proposed in this paper for determining the net section tension capacity of a cold-formed steel channel brace bolted at the web. The proposed equation is demonstrated through laboratory tests on low-ductility channel braces having practical aspect ratios that were bolted onto flexible plates, to be more reliable than the code equations and those existing in the literature. [ABSTRACT FROM AUTHOR]

A limited amount of data exists on the cyclic behavior of concrete-filled steel deck diaphragms, and the few historical testing programs that have been conducted used specimens that may not be representative of modern floor assemblies typical in North America. As part of a larger research project, the Steel Diaphragm Innovation Initiative, an experimental program was conducted to fill critical knowledge gaps related to the behavior and design of concrete-filled steel deck diaphragms leading to a better understanding of the seismic performance of steel buildings utilizing these types of diaphragms. The experimental program included eight diaphragm specimens that were approximately 4 m by 5 m, tested in a cantilever test setup wherein one edge is restrained against translation while the opposing edge is subjected to an in-plane cyclic displacement history. Parameters that were varied included deck height (51 mm and 76 mm), concrete cover over the deck (51 mm to 115 mm), concrete type (normal weight and lightweight), configuration of perimeter headed shear studs, and the presence and amount of reinforcing steel. Specimen behavior was quantified including initial stiffness, peak shear strength, ductility, and energy dissipation and qualitatively connected to observed cracking and deformations. The results of this experimental program, combined with tests from the literature were used to develop proposed expressions for peak shear strength and initial stiffness. The proposed expressions reasonably capture the experimental results and are suitable for design. [ABSTRACT FROM AUTHOR]

This paper examines the accuracy of design equations specified in the North American, European and Australasian codes for cold-formed steel structures in determining the net section tension capacity of bolted connections in flat steel sheets. It points out that the shear lag factors embedded in the code equations either yield 'anomalous' results or become irrelevant when they exceed unity. The 'anomaly' was demonstrated through laboratory tests and is explained by using simple calculus. The configurations of specimens tested in the laboratory include single shear- and double-shear connections, with single or double bolts in a line parallel or perpendicular to the force. A proper mathematical expression for the in-plane shear lag factor, which does not suffer from the anomaly of the code equations and never implies shear lag factors greater than unity for any configuration, is presented and shown to yield improved results compared to the current specifications. The resistance factor of 0.8 for the proposed equation is computed with respect to the load and resistance factor design (LRFD) approach specified in the North American specification for the design of cold-formed steel structures. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study on the critical buckling load and lateral bracing force of metal plate connected wood truss assemblies. Material property tests—including the modulus of elasticity of dimension lumber, flexural stiffness of plywood panels, and load-slip relationship of nail connection—and full-scale tests of individual trusses and truss assemblies were conducted. The critical buckling load and lateral bracing force were recorded. The continuous lateral bracing, the load sharing and distribution effects, and the residual deformation at the metal plate connections were studied for their influence on the system’s stability performance. The adequacy of the 2% rule of thumb, which is used by some design engineers for lateral bracing system design, was also discussed by comparing to the test results of the lateral bracing forces. The generated database can be used as input parameters and for verification for numerical analysis models and therefore contributes to the improvement of the design methods in the long term. [ABSTRACT FROM AUTHOR]

Formed from a thick layer of polystyrene foam sandwiched between two layers of oriented strand board, structural insulated panels (SIPs) are a viable alternative to traditional wood stud shear walls. Developed in North America, SIPs satisfy building performance criteria while being both sustainable and cost effective. This paper details a comprehensive experimental and parametric study at Napier University examining the structural performance of shear walls constructed of SIPs under the action of both racking loads and combined bending and axial compression. The effects of size and position of openings, for doors and windows, were examined and compared to designs carried out in accordance with BS 5268 and Eurocode 5. The study has demonstrated that SIPs perform as an effective composite material possessing the strength and stiffness necessary to sustain required design loads. [ABSTRACT FROM AUTHOR]

Embedded plates (EPs) are commonly used to connect steel to reinforced concrete elements. Due to a lack of industry-wide standard designs, EPs are custom designed for every instance in each project. This leads to many inefficiencies in the construction process and introduces susceptibilities to error. North American design standards based on the concrete capacity design (CCD) philosophy require many assumptions to predict EP capacity, which then lead to inconsistencies in their application. CCD is also well suited for analysis as it depends on a considerable numbers of variables (e.g., edge distances, anchor size, number, and length) to check capacity. The sheer number of variables makes it difficult for designers to come up with a trial design to fit a situation. This study aims to improve the efficiency of this process by proposing standard EPs. A subset of these proposed standard EPs are then experimentally tested to verify predicted capacities and evaluate design assumptions using existing CCD approaches in North America. Four- and six-anchor proposed standard EPs with shear tab connections were placed at four distances from the concrete edge (75–250 mm) and tested in shear towards the edge. North American provisions for concrete anchorage were adequate in predicting the failure loads if connection eccentricity, caused by the gap between the shear tab bolt line and the exposed surface of the plate, is considered in capacity predictions. Mean test-to-predicted ratios of 0.92 and 1.05 were obtained, respectively, when not considering and considering this eccentricity. Rotations of these connections during testing (0.01 to 0.02 rad at peak load with further rotations post-peak) and signs of secondary tension breakout cones suggest that connection eccentricity significantly affects the behavior of EPs and should be considered in design. [ABSTRACT FROM AUTHOR]

This paper presents shake table test results on two identical 1:0.429 scaled, 8-story moderately ductile RC shear wall specimens under the expected high-frequency ground motion in eastern North America. The walls were designed and detailed according to the seismic provisions of the NBCC 2005 and CSA-A23.3-04 standards. The objectives were to validate and understand the inelastic responses and interaction of shear and flexure and axial loads in the plastic hinge zones of the walls taking into consideration the higher-mode effects. One specimen was tested under incremental ground motion intensities ranging from 40 to 120% of the design level. The intensity range was increased from 100 to 200% for the second specimen. The response of the walls was significantly affected by the second mode, causing an inelastic flexural response to develop at the base as well as at the sixth level. Dynamic amplification of the base shear forces was also observed in both walls. In the second wall, which was tested in the undamaged condition, peak base shear forces occurred prior to significant inelastic rotation and the contribution to concrete of shear resistance exceeded the value used in the design. Once inelastic rotation had developed that contribution corresponded to the value obtained using a value of 0.18 for the reduction factor accounting for concrete cracking. Inelastic rotation in the upper wall region was found to limit the force demand imposed by the higher-mode response. [ABSTRACT FROM AUTHOR]

Ground-motion suite selection for Eastern North America (ENA) is distinguished from suite selection for high seismic regions by uncertainty related to earthquake intensity, spectral shape, and the wide range of relevant periods experienced by low-ductility structures. Whereas trends in high seismic regions point toward developing smaller, more efficient suites for use in practice based on reliable intensity parameters, current research on moderate seismic regions requires the development of ground-motion suites capable of exciting the widest range of structural periods while accounting for uncertainty related to ground-motion intensity. This paper discusses uncertainty related to ENA ground motions in terms of the logic tree in the probabilistic seismic hazard analysis (epistemic uncertainty) and the deaggregation of hazard into magnitude and distance bins (aleatory uncertainty), recommends a suite selection process for addressing this uncertainty without amplitude scaling, and evaluates the effectiveness of a specific suite in the context of reliability-based performance assessment procedures. [ABSTRACT FROM AUTHOR]

Cold-formed steel roof truss systems that use complex hat shape members for both top and bottom chord elements are a growing trend in the North America steel framing industry. When designing cold-formed steel sections, a structural engineer typically tries to improve the local buckling behavior of the cold-formed steel elements. The complex hat shape has proven to limit the negative influence of local buckling. However, a distortional buckling mode can be the control mode of failure in the design for the chord member with an intermediate unbraced length. The chord member may be subjected to both bending and compressive load because of the continuity of the top and bottom chord members. These members are not typically braced between each panel point in a truss. Numerical analyses using finite strip and finite element procedures were developed to compare with experimental results. A parametric study on geometric imperfection was also conducted to investigate the factors that affect the ultimate strength behavior of a particular complex hat shape. Better understanding of the flexural behavior of these complex hat shapes is necessary to obtain efficient, safe designs of a truss system. The results of these analyses will be presented in the paper. [ABSTRACT FROM AUTHOR]

Prescriptive design is a common practice in North America for low-rise light wood frame buildings. The prescriptive wood-based shear wall details provided in building codes to resist lateral loads were largely derived based on a combination of historical performance and engineering analysis. Inherent within the historical performance assumption is the presence of certain elements such as internal partitions that contribute to direct load resistance and structural redundancy. This inherent assumption is sometimes challenged by design engineers and proponents of alternative lateral load–resisting systems. In an attempt to showcase the contributions of the partition walls, a number of archetypes with various quantities of partitions were analyzed using a finite-element program. In the finite-element models, the wood-based structural shear walls and partition walls with gypsum wallboard were modeled as macroelements, with mechanical properties obtained from previous tests. Assumptions were made for the diaphragm and connection stiffness values. The results show a significant contribution of the partition walls to the lateral load resistance of light wood frame buildings. Partition walls accounted for 55%–71% of the overall lateral resistance of the evaluated buildings. Furthermore, diaphragms and wall-to-diaphragm connections contribute significantly to the overall behavior of the structures. [ABSTRACT FROM AUTHOR]

The current design rules of double shear bolted connections in the North American and Australian/New Zealand specifications for cold-formed steel structures are mainly based on the design rules of single shear bolted connections. The design rules may not be applicable for elevated temperature conditions because the design rules of single shear bolted connections were based on tests conducted at ambient temperature. A total of 153 double shear bolted connection specimens were tested, where 102 specimens were tested using a steady-state test method and 51 specimen tests were conducted using a transient-state test method. Three thicknesses of thin sheet steel were used in the investigation. The connection strengths obtained from the tests were compared with the nominal strengths calculated from the North American, Australian/New Zealand, and European specifications for cold-formed steel structures. The current modification factor in the bearing strengths calculation for double shear bolted connections was evaluated at an ambient temperature. The reduced tensile strengths of the thin sheet steels obtained from tensile coupon tests at elevated temperatures were used to calculate the nominal strengths of the connections. It is shown that the strengths of the double shear bolted connections predicted by the three specifications are generally conservative at elevated temperatures. Five failure modes were observed in the tests: bearing, tear-out, net section tension, bolt shear, and material. [ABSTRACT FROM AUTHOR]

This article presents 93 unpublished experimental results for rupture in the net section of bolted connections in cold-formed steel angles and channels. The article includes a study of the strength reduction coefficient in order to account for the shear lag effect. Predictions of connection strength by Brazilian and American design codes are considered. By comparing experimental results with design code predictions, model error (professional factor) statistics are evaluated. Model errors are incorporated in reliability analyses of typical connections to investigate their effects on connection safety. It is shown in the article that model errors have a significant impact on connection safety. Consideration of model errors leads to significant reductions in reliability indices, which are found to be less than the recommended target reliability levels. The model error statistics obtained herein are used to find the resistance factors that would be required to achieve the target reliability index in the design of bolted connections for net-section rupture. These factors are smaller than the current used in the American Iron and Steel Institute code. Other suggestions for improvement of the North American code are also presented. [ABSTRACT FROM AUTHOR]

The global seismic response of 3- and 8-story eccentrically braced frames (EBFs), designed for western and eastern North American locations, is studied using nonlinear time history analysis. Analytical models were built in three computer programs. Similar maximum forces were obtained, but the inelastic deformation predictions at the element and global structural levels showed sensitivity to the modeling employed. This feature should be considered in seismic performance assessment or design. Current design methods failed to predict interstory drifts and plastic link rotations, but the study confirmed the strong correlation between the two parameters associated with rigid-plastic behavior. The influence of yielding and flexural buckling of frame members, other than the links on the global frame performance, was evaluated using the OpenSees model. It was confirmed that the flexural yielding of outer beams is acceptable for EBFs with short and intermediate links, if the combined flexural strength of the braces and beams is at least equal to the expected end-link moments and the braces can resist the associated axial force-bending moment demand. Inelastic response of braces and columns in such frames did not negatively impact the overall frame behavior. [ABSTRACT FROM AUTHOR]

A study investigating the modal properties and dynamic response of several laboratory-constructed and in situ floors supported with cold-formed steel C-shaped joists for floors was conducted. The tested floors were typical of residential midrise applications, with oriented-strand board, FORTACRETE, and cold-formed steel deck subfloors, both with and without lightweight concrete topping. Details including span, large lip-reinforced web openings, subfloor, topping, strongback, and framing condition were varied to observe their influence on the fundamental frequency, damping ratio, and deflection. Suggestions for the design and remediation of floors where vibration serviceability is a concern are given. Laboratory tested floor systems were generally found to be the worst-case scenario for the natural frequency and damping ratio. Furniture and finishes were found to not appreciably change the performance of a floor system. The responses of the floor systems tested in this study were evaluated against the ISO 2631 limit for maximum acceleration and Onysko’s static deflection limit, as presented in ATC Design Guide 1: Minimizing Floor Vibration. The in situ floors examined were found to have performed within the acceptable range, as defined by the two criteria. [ABSTRACT FROM AUTHOR]

A testing program has been carried out on typical bridging components and connections used in North American practice to provide bracing to cold-formed lipped cee-studs, in order to determine the in-plane and out-of-plane strength and stiffness of the bridging components and connections. Bridging systems tested included cold-formed bridging channels directly welded to the stud, bridging channels connected to the stud web through a welded connection to a clip angle, and bridging channels connected to the stud web through a screwed connection to a clip angle. Bridging connections were loaded axially (into the stud web) and laterally (parallel to the stud web). Separate analysis of the test results indicates that, within the range tested, conventional bridging used in current North American practice has adequate stiffness and strength to brace axially loaded and curtain wall steel studs. [ABSTRACT FROM AUTHOR]

Studies the out-of-plane evaluation and retrofit of masonry walls from an old three-story residential building in North America. Wall construction technique; Retrieval and properties of the wall specimens; Retrofit techniques; Experimental procedure; Theoretical strength of wall specimens; Experimental results; Variation of dynamic properties; Analysis of the results; Comparison with analytical predictions; Conclusion.